This invention relates to a terminal crimping structure and a terminal crimping method in which a metal terminal having a pair of crimping piece portions extending upwardly respectively from opposite side edges of a base plate portion thereof is crimped (press-clamped) to a copper alloy wire of an electric wire, and the invention also relates to a wire harness having this terminal crimping structure.
For example, there is known one related metal terminal in which a compression rate A {=(a cross-sectional area of that portion of a conductor surrounded by crimping piece portions/a cross-sectional area of the conductor before crimping) which is the ratio of (the cross-sectional area of the conductor after crimping)/(the cross-sectional area of the conductor before crimping) is set to 80% to 85% (see, for example, JP-UM-A-3005065).
Usually, core wires of electric wires are different in the value of a strain in an initial condition before crimping, depending on their material and processing. And besides, even when the cores wires are subjected to the same compression, the core wires are different in the amount of change of a tensile strength per unit area. Therefore, the compression rate need to be determined taking the material and processing of the core wire of the electric wire into consideration.
In the JP-UM-A-3005065, however, the compression rate is not determined taking the material and processing of the core wire of the electric wire into consideration, and therefore it is difficult to secure a desired mechanical performance and a desired electrical performance.